Apparatus and method of data processing through serial bus

ABSTRACT

Data is received which is transmitted through a serial bus in a predetermined transmission band. The serial bus is preferably in conformity with the IEEE 1394 standards. One of recording modes for different recording rates is selected in accordance with the transmission band of the received data. The data is recorded in the selected recording mode. Data is reproduced which has been recorded in a recording mode for a predetermined recording rate. A transmission band is allocated, based on the recording mode, for transmitting the data through a serial bus.

BACKGROUND OF THE INVENTION

The present invention relates to processing of data that is received orto be transmitted through a serial bus. Particularly, this inventionrelates to recording and reproducing data that is input through a serialbus, and also outputting the video data through the same bus inconformity with the IEEE (Institute of Electrical and ElectronicsEngineers) 1394 standards. This serial bus is called 1394 serial bushereinafter.

Video tape recorders (VTRs) are well known audio and video equipmentthat encode video signals under the DV (Digital Video) standards definedin the IEC (International Electrotechnical Commission) 61883 standards,and outputs the encoded video signals through the 1394 serial bus.

The DV standards define the SD (Standard Definition) mode and HD (HighDefinition) mode. The SD mode offers recording and reproduction of videosignals having definition, such as, NTSC (National Television SystemCommittee) video signals. The HD mode offers recording and reproductionof video signals, such as, high vision signals. However, in the DVstandards, VTRs for the SD mode only have been on the market.

The encoding processing under the DV standards limits the amount ofencoded vide signals per frame within a predetermined amount. The SDmode thus defines the fixed recording rate that is 25 Mbps for recordingthe encoded video signals on a magnetic tape.

The encoded video signals are output through the 1394 serial bus perpacket under the DV standards after the transmission band is allocatedin accordance with the recording rate for recording the encoded signals.In detail, the IEC 61883 standards define the plug control to storeinformation needed for the transmission band into addresses that areaccessible through the 1394 serial bus. The transmission band is thenallocated using the information.

The amount of video signals varies when processed by VTRs at differentdata rates, and hence several transmission bands are also required onthe 1394 serial bus in accordance with the different data rates.

For example, the packet size for an MPEG (Moving Picture Coding ExpertsGroup) transport stream through the 1394 serial bus varies according tothe data rates. This transport stream is called MPEG2TS hereinafter.

The wider the transmission band is allocated for the MPEG2TS, the moreunnecessary bus resources are used. On the other hand, the narrower thetransmission band, the more unstable is the data transmission due toviolation of the communication protocols.

Furthermore, a user has to set the data recording mode for each inputMPEG2TS, which is a cumbersome operation.

SUMMARY OF THE INVENTION

A purpose of the present invention is to provide an apparatus and amethod of processing data that is received or to be transmitted througha serial bus, that achieve effective usage of bus resources.

Another purpose of the present invention is to provide an apparatus anda method of recording and reproduction of data that is received or to betransmitted through a serial bus, that achieve effective usage of busresources with no user recording mode setting.

The present invention provides a signal processing apparatus having: aprocessor to encode an input signal at a predetermined data rate togenerate encoded data; and a digital interface to allocate atransmission band for the encoded data based on the data rate fortransmitting the encoded data through a serial bus.

Furthermore, the present invention provides a signal processingapparatus having: a digital interface to detect a transmission band ofdata input through a serial bus; and a processor to decode the inputdata based on the transmission band for outputting a decoded signal.

Moreover, the present invention provides a recording and reproducingapparatus having: a digital interface to transmit or receive datathrough a serial bus, the interface allocating a transmission bandbefore data transmission; a recording and reproducing section to recordand reproduce the data at least in one of a plurality of recording modesfor different recording rates; and a controller to control the interfacefor changing the allocated transmission band in accordance with therecording mode for the data reproduced by the recording and reproducingsection.

The present invention also provides a recording and reproducingapparatus having: a digital interface to transmit or receive datathrough a serial bus in a predetermined transmission band; a recordingand reproducing section to record and reproduce the data at least in oneof a plurality of recording modes for different recording rates; and acontroller to control the recording and reproducing section forselecting one of the recording modes in accordance with the transmissionband of the data received by the interface.

The present invention further provides a method of signal processing. Aninput signal is encoded at a predetermined data rate to generate encodeddata. A transmission band is allocated for the encoded data based on thedata rate for transmitting the encoded data through a serial bus.

Moreover, the present invention further provides a method of signalprocessing. A transmission band of data input through a serial bus isdetected. The input data is decoded based on the transmission band foroutputting a decoded signal.

The present invention also provides a method of data processing. Data isreproduced which has been recorded in a recording mode for apredetermined recording rate. A transmission band is allocated, based onthe recording mode, for transmitting the data through a serial bus.

Furthermore, the present invention provides a method of data processing.Data is received which has been transmitted through a serial bus in apredetermined transmission band. One of a plurality of predeterminedrecording modes for different recording rates is selected in accordancewith the transmission band of the received data. The data is recorded inthe selected recording mode.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a block diagram of a recording and reproducing apparatusaccording to the present invention; and

FIG. 2 shows a block diagram of a modification of a recording andreproducing apparatus according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments according to the present invention will bedisclosed with reference to the attached drawings.

FIG. 1 shows a block diagram of a recording and reproducing apparatusaccording to the present invention.

An MPEG2TS is input to or output from an IEEE1394 interface (IF) 1through a 1394 serial bus.

The input MPEG2TS is supplied to a signal processor 2 for errorcorrection, etc. The output of the signal processor 2 is supplied to arecorder/reproducer 3 for modulation. The modulated MPEG2TS is stored ina storage medium 4.

The stored MPEG2TS is then retrieved and demodulated by therecorder/reproducer 3, and applied error correction, etc., by the signalprocessor 2. The MPEG2TS is supplied to and output from the IEEE13941F 1through the 1394 serial bus. Or, the MPEG2TS is supplied to an MPEGprocessor 5 and decoded to be an output video signal.

On the other hand, an input video signal is encoded by the MPEGprocessor 5, and then stored in the storage medium 4 through the signalprocessor 2 and the recorder/reproducer 3, or output from the IEEE13941F1 to the 1394 serial bus.

The recording and reproducing apparatus shown in FIG. 1 is furtherprovided with a CPU 6 that communicates with the IEEE13941F 1, thesignal processor 2, the recorder/reproducer 3 and the MPEG processor 5for changing the data rate of the signal processed by these circuitry. Auser can enter several commands to the CPU 6 via a user interface (IF)7.

The recording and reproducing apparatus according to the presentinvention is offered several recording modes for different datarecording rates.

In detail, the recording rate for recording (storing) the signal in thestorage medium 4 is set in accordance with the transmission band of anMPEG2TS supplied by the IEEE13941F 1. Or, the transmission band of anMPEG2TS output by the IEEE13941F 1 to the 1394 serial bus is allocatedin accordance with the data rate of the signal reproduced from thestorage medium 4.

Disclosed in detail first is recording (storing) a video signal in thestorage medium 4, which is input via the IEEE13941F 1 or the MPEGprocessor 5.

The user selects one recording mode among several modes for recording avideo signal that is input via the MPEG processor 5. The recording modesare the first mode for the lowest recording rate B1, the second mode forthe intermediate recording rate B2, and the third mode for the highestrecording rate B3.

When the user selects, for example, the second recording mode, a modeselection request is entered to the CPU 6 via the user IF 7. The CPU 6sends a control signal to the signal processor 2, therecorder/reproducer 3 and the MPEG processor 5 for recording at the datarate B2. The control signal is also sent to the IEEE13941F 1 for dataoutput at the data rate B2.

The recording processing in the second mode is executed as follows:

An input video signal supplied to the MPEG processor 5 is transformedinto an MPEG2TS having a data rate that does not exceed the recordingrate B2. The MPEG2TS is supplied to the signal processor 2 and appliedaddition of headers and error correction codes, and shuffling for makingthe data amount uniform for data blocks, etc., and supplied to therecorder/reproducer 3. The processed MPEG2TS is then modulated in therecorder/reproducer 3 and stored in the storage medium 4.

Furthermore, the CPU 6 allocates a transmission band (transmission rateR2) for outputting the MPEG2TS having the recording rate B2 from theMPEG processor 5 to the 1394 serial bus via the IEEE13941F 1.

The data rate of the MPEG2TS output from the MPEG processor 5 iscontrolled so as not to exceed the recording rate B2. The MPEG2TS isthen output from IEEE13941F 1 in the transmission band that is allocatednot based on the data rate of the video signal input to the MPEGprocessor 5 but the control signal sent by the CPU 6.

When the user selects an MPEG2TS input via the IEEE13941F 1 forrecording, the CPU 6 sends a control signal to the IEEE13941F 1 forcommunication with an external apparatus (not shown) that hastransmitted the MPEG2TS through the 1394 serial bus. The IEEE13941F 1calculates the transmission band allocated to the MPEG2TS based on theinformation required for allocating transmission band and stored in aregister called OPCR (Output Plug Control Resister defined by the IEC61883 standards). The recording mode is also selected based on theinformation.

Suppose that the first recording mode is selected.

An MPEG2TS input through the 1394 serial bus is supplied to the signalprocessor 2 via the IEEE13941F 1 for addition of headers and errorcorrection codes and shuffling.

The output of the signal processor 2 is supplied to therecorder/reproducer 3 for modulation. The modulated MPEG2TS is stored inthe storage medium 4 in the first recording mode.

The input MPEG2TS is also supplied to the MPEG processor 5 via theIEEE13941F 1. The MPEG2TS is decoded under the control signal from theCPU 6, and output as a video signal.

Disclosed next is reproduction of an encoded video signal stored in thestorage medium 4.

Suppose that the encoded video signal (MPEG2TS) has been stored in thestorage medium 4 in the third recording mode.

The signal is retrieved and supplied to the recorder/reproducer 3 fordemodulation. The recorder/reproducer 3 then sends informationindicating the third recording mode to the CPU 6.

In response to the information, the CPU 6 sends a control signal to thesignal processor 2 for error correction, etc., and to the IEEE13941F 1for allocation of a transmission band to transmit the MPEG2TS that hasbeen recorded (stored) at the recording rate B3, through the 1394 serialbus.

The control signal is also sent to the MPEG processor 5 for decoding andoutputting a video signal.

The data rate of the video signal retrieved from the storage medium 4never exceeds the recording rate B3. The transmission band fortransmitting an MPEG2TS via the IEEE13941F 1 is allocated based on thecontrol signal from the CPU 6, not the data rate of the MPEG2TS outputby the signal processor 2.

Disclosed next is encoding an input video signal into an MPEG2TS whichis to be output via the IEEE13941F1 without recording and reproduction.

Suppose that the user selects the second recording mode (recording rateB2) via the user IF 7.

The CPU 6 sends a control signal to the MPEG processor 5 for encoding aninput video signal at a data rate below the recording rate B2.

The output of the MPEG processor 5 is supplied to the IEEE13941F 1 forallocating a transmission band based on the control signal from the CPU6. An MPEG2TS is then output by the IEEE13941F 1 to the 1394 serial busin the allocated transmission band.

Disclosed next is decoding an input MPEG2TS into a video signal which isto be output via the MPEG processor 5, without recording andreproduction.

The CPU 6 sends a control signal to the IEEE13941F 1 to communicate withan external apparatus (not shown) that has transmitted an MPEG2TSthrough the 1394 serial bus. The IEEE13941F 1 calculates thetransmission band allocated to the MPEG2TS.

The MPEG2TS is supplied to the MPEG processor 5 and decoded into a videosignal to be output based on the calculated transmission band.

As disclosed above, a transmission band is allocated in accordance witha recording mode for transmitting an MPEG2TS through the 1394 serialbus.

This transmission band allocation achieves continuous transmission ofsignals retrieved from a storage medium for, for instance, a pluralityof video programs having different data rates stored therein with norequirement of the reallocation of transmission band in accordance withthe different data rates, when the programs have been stored in the samerecording mode.

The same achievement goes to one video program for which the data ratevaries with no requirement of reallocation of transmission band inaccordance with the varying data rate, when the program has been storedin the same recording mode from the beginning to end.

Moreover, this transmission band allocation requires no addition of datarates of a plurality of video programs stored in a storage medium as oneMPEG2TS, for transmission of the programs simultaneously through the1394 serial bus.

Not only that, quick reallocation of transmission band is achieved forrecording mode that is varying during retrieval from a storage medium.

Change in recording mode from high to low recording rate does not affectcontinuous data transmission even during transmission band adjustment.

Furthermore, the quick allocation of transmission band overcomes theproblem in that change in recording mode from low to high recording ratewould force intermittent data transmission.

Recording of an MPEG2TS input through the 1394 serial bus in thisinvention offers recording mode selection in accordance with payloadsize of an MPEG2TS input through the 1394 serial bus. The recording modeis thus automatically selected that fits the transmission band of theinput MPEG2TS with no requirement of user mode setting. This modeselection achieves effective data recording in a storage medium.

The signal (or data) described so far is a video signal. It is, however,understood that an audio signal can also be transmitted or received viathe IEEE1394 IF 1, with a video signal.

The recording and reproducing apparatus of FIG. 1 includes the MPEGprocessor 5. It can, however, be omitted as shown in FIG. 2.

The communications between the CPU 6 and the IEEE13941F 1, the signalprocessor 2, the recorder/reproducer 3 and the MPEG processor 5 areachieved by control programs stored on the CPU 6. The software isprogrammed in accordance with the specification of each circuitry, whichis understandable for ordinary skilled persons in the art; and hence notdisclosed for brevity.

As disclosed above, according to the present invention, data retrievedfrom a storage medium is output to the 1394 serial bus via the IEEE1394interface in a transmission band that is allocated in accordance withthe recording mode for the MPEG2TS when recorded. The transmission bandallocation achieves data transmission with effective usage of busresources.

Furthermore, according to the present invention, the recording rate isset in accordance with the transmission band of data input via theIEEE1394 interface. The recording rate setting achieves effective datarecording with no user recording mode setting.

1-12. (canceled).
 13. A data output apparatus comprising: an outputsection to output data in an output mode selected among a plurality ofoutput modes for different output rates; a digital interface connectedto external equipment through a serial bus, to allocate a transmissionband before data transmission and then transmit the data to the externalequipment through the serial bus in the allocated transmission band; anda controller to control the output section for data output and thedigital interface for data communication, wherein when outputting thedata to the external equipment, the output section outputs the data inthe output mode selected among the output modes, the controller controlsthe digital interface so that the digital interface can allocate thetransmission band corresponding to the selected output mode, and thedigital interface transmits the data to the external equipment in theallocated transmission band.
 14. The apparatus according to claim 13,wherein the serial bus ins in conformity with the IEEE (Institute ofElectrical and Electronics Engineers) standards.
 15. A data outputmethod comprising the steps of: outputting data in an output modeselected among a plurality of output modes for different reproducingrates; allocating a transmission band before data transmission;transmitting the data through a serial bus in the allocated transmissionband; and controlling data output and data transmission, wherein whenoutputting the data and transmitting the data through the serial bus,outputting the data in the output mode selected among the output modes,allocating the transmission band corresponding to the selected outputmode, and transmitting the data through the serial bus in the allocatedtransmission band.
 16. The method according to claim 15, wherein theserial bus is in conformity with the IEEE (Institute of Electrical andElectronics Engineers) standards.